Get last run action from application object

**Is your feature request related to a problem? Please describe.**
We can get the next action, we need the current.

**Describe the solution you'd like**
`app.get_next_action()` -- available
`app.get_prior_action()` -- not avaialble 

**Describe alternatives you've considered**
Current/prior, need to make semantics clear

**Additional context**
See #501
